Mexico has raised the alert level for the Popocatepetl volcano due to increasing activity. It's now at the fifth step on a seven-level warning scale.
A lava dome is growing in the volcano's crater, the National Disaster Prevention Center said on Tuesday. The 17,886-foot volcano also has been spewing fragments of incandescent rock recently, as well as water vapour and ash.
The volcano could experience "significant explosions of growing intensity that hurl incandescent rocks significant distances," large ash showers and possible flows of mud and molten rocks down the volcano's flanks, the centre said.